private void VisualCanvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { var pointClicked = e.GetPosition(CanvasPanel); if (rbAdd.IsChecked == true) { var visual = new DrawingVisual(); DrawSquare(visual, pointClicked, false); CanvasPanel.AddVisual(visual); } else if (rbDelete.IsChecked == true) { var visual = GetVisual(pointClicked); if (visual != null) { CanvasPanel.RemoveVisual(visual); } } else if (rbSelected.IsChecked == true) { var visual = GetVisual(pointClicked); if (visual != null) { var topLeftCorner = new Point(visual.ContentBounds.TopLeft.X + DrawingPen.Thickness / 2, visual.ContentBounds.TopLeft.Y + DrawingPen.Thickness / 2); DrawSquare(visual, topLeftCorner, true); // 重绘为黄色 ClickOffet = topLeftCorner - pointClicked; IsDragging = true; if (SelectedVisual != null && SelectedVisual != visual) { ClearSelection(); // 将原来为黄色的重绘为淡蓝 } SelectedVisual = visual; } } else if (rbSelectMultiple.IsChecked == true) { SelectionSquare = new DrawingVisual(); CanvasPanel.AddVisual(SelectionSquare); SelectionSquareTopLeft = pointClicked; IsMultiSelecting = true; CanvasPanel.CaptureMouse(); } }